JP2002229286A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such problems in a space-saving copying machine, that a jam easily occurs and is difficult to remove because it occurs within such a small machine. SOLUTION: The image forming device has a paper storage part which stores sheets of paper, a paper feed means which feeds the sheets of paper stacked in the paper storage part to a carrying path, an electrophotographic image forming means having a developing device provided with a developing roller adapted to form a toner image on a photoreceptor drum, a transfer fixing belt which transfers the toner image, formed by the image forming means, in a primary transfer position, further transfers the toner image to the sheet of paper in a secondary transfer position, and fixes the toner image by holding and hearting the toner image between the transfer fixing belt and a pressure roller located opposite the belt in the secondary transfer position, and further, an ejection means which ejects the sheet of paper. The transfer fixing belt is longitudinally disposed directing substantially upward. The secondary transfer is carried out in the lowermost part of the transfer fixing belt. The position of the paper feed means, the paper transfer position, and the position of the ejection means are disposed on a substantially straight line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a digital copying machine,
The present invention relates to a facsimile, a printer, and a multifunction peripheral having these functions.

[0002]

2. Description of the Related Art Conventionally, an analog type copying machine that has been used for a long time has an original reading unit on an upper surface of an image forming apparatus main body, a paper feed cassette laid out on a side surface, and a paper discharge unit on the opposite side. However, it was very disturbing where the horizontal size was large and there was not much office space. FIG. 4 shows a typical example. The conventional example 1 includes a sheet feeding unit 51, a conveyance path 52, a pair of registration rollers 53, an image forming unit 54, a fixing unit 55, a pair of discharge rollers 56, a discharge tray 57, and an automatic document feeder 5.
8, optical section 59, and the like. Paper cassette (5
11 to 513) passes through the transport path 52, temporarily stops at the registration roller pair 53 for synchronization with the reading timing of the original, and alignment of the leading edge of the paper. The toner image is transferred by the forming section 54, and subsequently, the toner image is fixed by being nipped and heated by the heat roller and the pressure roller at the fixing section 55, and thereafter discharged to the paper output tray 57. In such a configuration, a plurality of paper feed cassettes (511 to 513) are set from the right side in the figure, and a considerable distance to the left end of the paper discharge tray 57 is required. Further, since the sheet cassettes (511 to 513) are inserted and removed from the right direction, the installation condition that a space is substantially required in the direction where the cassette is located is required.
However, since the transport path 52 is substantially straight in the horizontal direction from the paper feeding to the discharging, it can be said that the occurrence of paper jam is small and the processing is easy. Since the lower part in the figure is not particularly used, it is often placed on a large desk or on a dedicated desk 60 with casters.

<Conventional Example 2> Therefore, a front loading type in which a drawer cassette capable of replenishing sheets from the entire surface is laid out under the main body of the image forming apparatus has appeared, and sheets are transferred from a sheet feeding cassette below an image forming unit. Paper feed, vertical conveyance, transfer of a toner image, fixing, and then discharge have become mainstream. As a result, since the cassette does not protrude in the lateral direction, considerable space saving can be realized. FIG. 5 is an example. In Conventional Example 2, the paper feeding unit 61 and the transport path 6
2, registration roller pair 63, image forming unit 64, fixing unit 6
5, double-sided branch 66, discharge roller pair 67, paper discharge tray 6
8, an automatic document feeder 69, a digital optical unit 70, a switchback unit 71, a two-sided conveying path 72, and the like.
In the case of one-eye printing, paper fed from either the paper feed cassettes (611 to 613) or the paper feed tray 614 is
After passing through the conveyance path 62, the image forming unit 64 temporarily stops at the registration roller pair 63 to synchronize with the timing of writing the latent image from the LSU to the photosensitive drum and align the leading edge of the sheet. The toner image is transferred onto one surface, and is subsequently nipped and heated by the fixing roller 65 between the heat roller and the pressure roller to fix the toner image by heating. In the case of double-sided printing, the paper printed on the first side is sent to the switchback unit 71 by the double-sided branching unit 66 to switch back the transport direction, joins the transport path 62 again, and is printed on the second side of the paper. Is discharged. However, in such a configuration, there is a problem that the transport distance from paper feeding to paper discharging is long even in one-sided printing. Immediately after the sheet is further fed, the sheet is conveyed vertically upwards against the gravity, and the direction is changed by 90 degrees. For this reason, the paper jam from the paper feed cassettes (611 to 613), especially the lower paper feed cassette 613, has a higher jam occurrence rate.

<Conventional example 3> In recent years, since the space to be discharged is also obstructive, the discharge of the paper is performed on the upper surface of the image forming apparatus, and the copying machine has been digitized. The optical path for exposing to the photoconductor drum is eliminated, and the photoconductor drum can be exposed by laser or LED, so there is no restriction on the layout, and copiers and printers that discharge inside the cylinder have appeared, enabling further space saving. Was. FIG. 6 shows an example. In the third conventional example, a paper feed unit 68, a conveyance path 82, a pair of registration rollers 83, an image forming unit 84, a fixing unit 85, a discharge port 86, an in-body discharge tray 87, an automatic document feeder 88, a digital optical unit 89 The paper fed from either the paper feed cassettes (811 to 813) or the paper feed tray 814 passes through the transport path 82, and the timing of writing the latent image from the LSU to the photosensitive drum is determined. Sync,
The toner image is temporarily stopped by the pair of registration rollers 83 to align the leading edge of the sheet, the toner image is transferred to the sheet by the image forming unit 84 at a certain timing, and then the fixing unit 85 is nipped and heated by the heat roller and the pressure roller. After the toner image is fixed, the toner image is discharged to the internal discharge tray 68. However, in such a configuration, more space can be saved, but the paper conveyance repeats a steep round, so that the occurrence rate of the jam increases.
Jam processing is also becoming difficult due to the more complicated transport path.

[0005]

As described above, as the above-mentioned conventional front loading method and the method of discharging the image onto the upper surface or the inside of the drum, the distance for transporting the paper becomes longer, and the sharp radius increases. It has come to be forced to reverse. For this reason, paper handling technology becomes complicated, and the occurrence of jam tends to increase. Further, since the paper transport path is complicated, the jam processing is also difficult, and it is necessary to provide an opening and closing mechanism everywhere, so that the entire image forming apparatus becomes large. In fact, when looking at a place where a jam has occurred in a copying machine or the like in recent years, the jam frequently occurs at a sharply curved portion of a round where the above-mentioned conveyance is impossible or at a confluence of sheets.

[0006] On the other hand, in recent years, from the viewpoint of resource saving, recycled paper, recycled paper, reuse of paper printed only on the front side, and poor quality paper such as rough paper have been used. It can be said that this tendency further increases the incidence of jams.

When looking at the usage of a copying machine in a general office, most use A4 plain paper. At present, other A3 paper and B-size paper are hardly used. Many workplaces do not copy any envelopes or postcards. However, even if the paper is of a size that is rarely used, the cassette is securely occupied by one level. For this reason, the place of frequently used paper is cut off, and the paper is frequently set.

As described above, the concept of the present invention is to make the frequently used paper as straight and short as possible. Except for cassettes that store frequently used sheets, paper is basically fed from the bypass. By performing the conveyance from the paper supply to the discharge in the horizontal direction or from the upper side to the lower side, the jam due to the slip is reduced. For a paper supply unit that is frequently used, a paper supply technology with high reliability is used.

[0009]

In order to solve the above problem, according to the first aspect of the present invention, a sheet storage section in which a plurality of sheets are stored and a sheet stacked in the sheet storage section are transported to a transport path. An electrophotographic image forming device having a developing device having a developing device for forming a toner image on a photosensitive drum, and a toner image formed by the image forming device at a primary transfer position The transfer and fixing belt transfers the toner image to the paper at the secondary transfer position, and fixes the toner image at the secondary transfer position by nipping and heating by an opposing pressure roller, and discharging the paper. Means, the transfer and fixing belt is disposed vertically elongated substantially upward, the secondary transfer is performed at the lowest position of the transfer and fixing belt, the position of the paper feeding means,
The image forming apparatus is characterized in that the transfer position on the sheet and the position of the discharge unit are substantially straight.

In the invention according to claim 2, the image forming means uses a vertical developing device in which a developing roller faces substantially upward of the photosensitive drum and a stirring means is arranged in a substantially vertical direction. The image forming apparatus according to claim 1 is used.

According to a third aspect of the present invention, there is provided the image forming apparatus according to the first or second aspect, wherein the toner storage container is laid out above the developing device and the transfer fixing belt.

According to a fourth aspect of the present invention, there is provided the image forming apparatus according to any one of the first to third aspects, further comprising a transfer fixing belt cooling unit for cooling the transfer fixing belt.

According to a fifth aspect of the present invention, a plurality of simplified paper feed trays and a common one thereof are provided above the paper storage unit.
And two paper feed trays, which can selectively feed paper from a plurality of simplified paper feed trays. The image forming apparatus according to any one of claims 1 to 4, wherein the image forming apparatus smoothly merges from the direction to the transport direction.

According to the present invention, the first discharge position for discharging the discharge tray and the second discharge position for allowing the user to easily take out the discharged paper are provided. The image forming apparatus according to any one of claims 1 to 5, further comprising a discharge tray lifting means.

According to a seventh aspect of the present invention, the sheet storage section can store a large amount of sheets of paper, is built in the main body of the image forming apparatus, and can be pulled out to the front. Is used.

[0016]

According to the first aspect of the present invention, the transfer / fixing belt is vertically disposed, and the secondary transfer is performed at the lowermost position of the transfer / fixing belt, and the transfer and the fixing are performed simultaneously. And the transfer and fixing are performed simultaneously, so that the distance between the registration roller and the discharging means can be reduced, and the paper transport distance can be shortened. In addition, the number of paper cassettes that are frequently used is reduced to one, and the distance from the paper feeding position to the discharge is substantially straight, so that the paper transport distance can be further reduced.

According to the second aspect of the present invention, the space can be further reduced by using the developing device that is vertically arranged.

According to the third aspect of the present invention, since the toner storage container is laid out above the transfer fixing belt and the developing device, the space formed by the toner storage container, the transfer fixing belt, and the developing device becomes vertically long, and the space for the paper is reduced. The transfer space for the toner image becomes shorter.

According to the fourth aspect of the present invention, the belt heated during fixing can be cooled by using the cooling means for cooling the transfer fixing belt. According to the fifth aspect of the present invention, since a plurality of simplified paper feed trays are used for feeding paper other than the main paper storage unit, paper that is rarely used can be fed from here. Since a plurality of paper trays are prepared, it is possible to set a plurality of types other than the main paper. Since the usage rate of the paper other than the main paper is less than a few percent of the whole paper, the other papers can be fed from the bypass at any time. Further, although the usage rate of the sheets other than the main sheet is low, the types of each sheet are large (small kinds and many kinds). Therefore, a plurality of simplified trays are provided. By providing a plurality of paper storage units, more types of paper can be set in a small space. In addition, since these simplified paper feed trays are located above the main paper storage unit, the paper is conveyed from above to below, and the slip of the conveyance rollers can be reduced.

According to the sixth aspect of the present invention, since the sheet is conveyed from the top to the bottom, the sheet is discharged downward. Therefore, this is compensated for by lifting the discharge tray. This is because, if a paper path is provided and the paper is discharged upward, paper that may curl after fixing is conveyed from the bottom to the top. Discharged paper does not jam.

According to the seventh aspect of the present invention, the distance from paper feeding to paper discharging can be further shortened by using a large-capacity paper cassette for the paper storage unit and incorporating the paper cassette in the main body of the image forming apparatus. . Furthermore, by using a drawer that can be pulled out over the entire surface, a space in the left-right direction is not taken up much. This is because the front loading system includes a special cassette, but the size is considerably large.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment employing the present invention will be described with reference to FIG. In the figure, the image forming apparatus includes a large capacity cassette 01, a sheet feeding unit 02, a registration roller pair 03,
, A conveyance path 04, an image forming unit 05, a transfer and fixing belt unit 06, a second transfer roller 07, a fixing unit 08, a discharge unit 09, a discharge tray 10, and a schematic feed tray 11. , Scanner 21 and automatic document feeder 2
2 and the like.

The large capacity cassette 01 and sheet feeding means will be described with reference to FIG. In this figure, the large-capacity cassette 01 includes a cassette frame 011 and a sheet stacking plate 01.
2. Sheet sensor 0121, sheet loading plate elevating means 013
Etc., and only the main paper is loaded. In a general office, the paper size that is often used is A4. In recent years, digital copiers and printers are mainly used, so that the A4 width can be output regardless of the direction in which the original is placed, and the horizontal direction is preferable in terms of the number of printed sheets per time. Since there is only one sheet feeding cassette, there is no space for other sheet feeding cassettes and no vertical conveyance path as described in the related arts 2 and 3, so that a large capacity can be realized. Even if a large-capacity cassette using higher components is used, the cost is not significantly increased because only one is used. The paper sensor 0121 detects the presence or absence of paper loaded on the paper loading plate 012 using a photo sensor or the like.

The sheet stacking plate elevating means 013 includes a motor (01321, 0131b) and a driving pulley (0132).
a, 0132b), wires (0133a, 0133)
b) and idle pulleys (0134a, 0134b). When feeding paper, the upper surface of the uppermost sheet loaded on the sheet loading means 01 and the sheet feeding means 02
Is controlled so that the distance of the portion for sucking the sheet is maintained at a predetermined distance. The predetermined distance is determined by various related parameters such as the air volume of the sheet blowing unit 023, the suction force of the sheet suction unit 022, the weight of the sheet per sheet, the sheet size, and the coefficient of friction between sheets. When the sheet is being conveyed, the distance between the sheet and the sheet to be fed next is such that the sheet to be fed next does not start moving due to the frictional force between the sheet and the sheet to be fed next. The distance is such that one sheet of paper can be attracted to the lower surface side of the paper feeding belt 021 by the air flow amount and the suction force of the paper suction means 022. Alternatively, the predetermined distance may be set in advance, and the other related parameters may be determined. Further, the sheet stacking plate elevating means 013 is used for replenishing sheets and performing sheet jam processing.
It also plays a role such as lowering to a predetermined position.

The paper feeding unit 02 includes a paper feeding belt unit 21, a paper suction unit 022, and a paper blowing unit 02.
The sheet blowing means 022 is configured to blow air from the downstream side in the sheet transport direction from the downstream side in the sheet conveyance direction through the air blowing port 0232 from the blowing fan 0231 to the upper part of the plurality of sheets stacked on the sheet stacking plate 012. The paper is blown by spraying. The paper feeding belt unit 021 has at least two rollers (0212, 021
3) and a plurality of belts (021) which are wound around the at least two rollers at substantially equal intervals and face the upper surface of the paper stacked on the paper stacking plate 012 on the downstream side in the paper transport direction.
1) and a part 0214 of a suction duct, and the paper suction means 022 is provided with a suction fan 022.
1 and a suction duct 0222. A plurality of paper suction holes (not shown) of the paper suction means 022 are provided, and when feeding paper from each of a plurality of holes of the belt, the paper stacking plate is provided. The uppermost one of the plurality of sheets stacked on the sheet No. 012 sucks the sheet to the lower surface of the plurality of belts 021, and further, when the belt is rotated to convey the sheet, the sheet is attracted to the lower surface. While being conveyed to the subsequent conveyance path 121.

Next, a basic operation of the image forming apparatus employing the above-described air suction type sheet feeding and conveying device will be described. First, it is determined whether or not there is a sheet on the sheet stacking plate 012. If there is no sheet, a paper empty is displayed and a replenishment of the sheet is requested. If there is a sheet, the distance between the lower surface of the sheet feeding belt and the upper surface of the uppermost sheet of the sheets stacked on the sheet stacking plate 011 is set to a predetermined distance, and the suction fan and the blowing fan 31 Check if it is working. Next, the paper is sucked by the lower surface of the paper feed belt 021. Subsequently, the paper feed belt 21 is rotated to transfer the paper to the paper feed path, and the paper feed belt is stopped. As described above, in the present invention, it is better to use a sheet capable of accurately feeding one sheet at a time even if it is slightly expensive.

The simplified paper feed tray 11 is provided with a plurality of paper feed trays similar to conventional bypass paper feeds. Here, the large-sized simplified paper feed tray 111, the medium-sized simplified paper feed tray 112, and the small-sized simplified paper feed tray 113
No matter when paper is fed from any of these, the paper feeding tray is inclined obliquely downstream of the paper feeding means 02 and upstream of the registration roller pair 03 via the bypass conveyance path 12 regardless of the paper feeding tray. Merges gently in the transport direction from above. For this reason, the fed paper does not go against gravity and the transport path does not have a particularly sharp curve, so that the occurrence of JAM is extremely reduced. Each paper feed roller is made of ordinary urethane rubber, EPDM, or the like, and may be a simple roller having a flat knurl around the periphery to prevent slippage, or a complicated roller such as a gate system. Since this simplified paper feed tray is assumed to be used infrequently, even if a simple paper feed roller is used, the wear is small and the replacement is easy, so that even a cheap paper feed tray plays a sufficient role. Usually, such a schematic paper feed tray is openable and closable, and when it is not used, it often closes with the cover of the image forming apparatus, but in this embodiment, there are a plurality of schematic paper feed trays. Therefore, it is easier to adapt the paper feeding position by providing the paper feeding position inside the image forming apparatus main body and expanding and contracting the tray.

The pair of resist rollers 03 is made by appropriately pressing a roller made of a resin such as polyacetal or the like with a slippery resin and a rubber roller, and firstly sliding the conveyed paper tip against the resin roller, and then nips the paper. By stopping the tip, the tip is arranged parallel to the transport direction. The registration roller pair 03 rotates in synchronization with the image timing. Although the drawing is performed for a sheet fed from the large-capacity cassette 01, the air tray is used for the sheet feeding and the distance from the sheet feeding to the transfer position is very short. , And the double-side refeeding only, the distance from sheet feeding to discharge can be further reduced.

The image forming means 05 will be described with reference to FIG. In the figure, the image forming unit 05 includes a photosensitive drum 051, a main charging device 052, an exposing unit 053, a developing device 054, a drum cleaner 056, a toner container 057, and the like. Especially developing device 054
Uses a vertical developing device. The positional relationship between the transport path 04 and the developing device 054 is such that it does not interfere with the registration roller pair 03.

The photosensitive drum 051 has undergone a charging and exposing process before the development process. The main charging device 052 charges the surface of the photosensitive drum 051 to a predetermined surface potential. An image formed by exposing information and forming an electrostatic latent image on the peripheral surface is rotating.
The main charging device 052 uses a corotron system, a scorotron system, a charging roller, or the like, and generates a corona discharge by applying a high voltage or charges the surface of the photosensitive drum 051 to a predetermined surface potential by injecting charges. Let me. Here, the exposure means 053 uses LPH (LED PRINT HEED) to save space. However, if space is possible, using LSU or the like will lower the cost.

The developing device 054 includes a developing housing 054.
1, a developing roller 0542, a supplementary cutting plate 0543, a first stirring means 0544, a second stirring means 0545, a pumping roller 0546, and the like. The developing housing 0541 is a housing of the developing device main body, maintains components of the developing device in a predetermined positional relationship, and is a tank for the developer. In general, the material is made of a resin containing glass fiber or the like to achieve dimensional accuracy. First stirring means 0544,
The second stirring unit 0545 uses a stirring paddle or a spiral to stir the developer including the carrier particles and the toner,
The toner is uniformly mixed by being conveyed, causing frictional charging to charge the toner.

The developing roller 0542 is disposed in the developing housing 0541 in parallel with the photosensitive drum 051, and has a sleeve member that rotates in a forward direction with respect to the rotational movement direction of the peripheral surface of the photosensitive drum 1; It is constituted by a magnet provided in the sleeve member. The sleeve member attracts and transports the developer to the peripheral surface, sends the developer to a developing area where a nip is formed with the photosensitive drum 051, and applies the developer to the electrostatic latent image on the peripheral surface of the photosensitive drum 051. Form a toner image. Here, an appropriate developing bias is applied to the first sleeve member, and an electrostatic latent image on the peripheral surface of the photosensitive drum 1 is formed by forming an electric field using the photosensitive drum 051 as a counter electrode. A toner image is formed. Generally, the material of the sleeve member is an aluminum alloy, and the peripheral surface thereof is subjected to knurling, sandblasting, and wire brushing in consideration of improvement in developer transport performance. The magnet has multiple magnetic poles in the radial direction, and is made of a ferrite-based permanent magnet (sintered or binder magnet).

The ear cutting plate 0543 is provided with a developing roller 0542.
And has an end located at a predetermined gap, and has a role of regulating the layer thickness of the developer conveyed on the peripheral surface of the developing roller 0542. As the material, metals such as stainless steel, brass, and aluminum alloy are used in consideration of abrasion resistance and prevention of toner adhesion. Setting the layer thickness requires precision.

The pumping roller 0546 is located at a position deviated from the developing area of the developing roller in the longitudinal direction, and when transferring the developer from the first stirring means 0544 to the second stirring means 0545, the pumping roller 0546 moves from the bottom to the top. In this case, the developer from the first stirring means 0544 is magnetically attracted to the surface of the pumping roller 0546 and is peeled off to the second stirring means 0545 by a simple blade.

The toner density detecting means 0547 uses a magnetic permeability sensor, and may be installed anywhere as long as the toner and the carrier particles are sufficiently stirred and the mixed developer flows.

Next, the flow of the developer will be described. First, the stirring of the developer is performed by circulating the first stirring means 0544 and the second stirring means 0545 via the pumping roller 0546. Further, the first stirring means 054
Reference numeral 4 agitates while circulating the developer to the developing roller 0542. The developing roller 0542 magnetically attracts and holds the developer on the peripheral surface by the magnetic poles of the magnets disposed inside the sleeve member, and the pumped developer is moved by the ear-cutting plate 0543 as the sleeve member rotates. The amount of the toner is regulated, and the toner is conveyed by the carrier magnetic pole and rises by the magnetic field generated by the main pole, and is sent to the developing area where the sleeve member and the photosensitive drum 051 are formed. After the development, the developer is continuously transferred to the first stirring means 0544 near the peeling magnetic pole of the same polarity adjacent to the internal magnet by the rotational movement of the sleeve member. This first stirring means 05
The developer having consumed the toner collected in 44 again becomes the first toner.
The toner is supplied and maintained at a predetermined density while circulating the stirring means 0544 and the second stirring means 0545 via the pumping roller 0546.

The toner container 057 is composed of a toner supply roller 0571, a toner feeding means 0572, and the like.
By rotating the toner replenishing motor, the toner replenishing roller 0571 is rotated, and the second developer agitating / conveying means 05 of the developing housing 0541 is opened through the lower opening.
The toner is dropped on the upstream side of 45. This toner drop is performed by comparing the toner density of the developer measured by the toner density detecting means 0547 with the set toner density, and replenishing the toner when the measured toner density is lower than the set toner density. Then, the toner supply is stopped when the measured toner density becomes higher than the set toner density. The toner feeding unit 0572 rotates so as to move the toner toward the opening, and is driven by the same driving as the driving of the toner supply roller 0571.

In the first transfer section, the transfer fixing belt 061
The toner image is transferred to the printer. The details here will be described later in the description of the transfer fixing belt. The drum cleaner 056 has a blade, and scrapes and collects the toner remaining at the first transfer position 1000 with the blade.

Next, the transfer / fixing belt unit 06 and the second transfer roller 07 will be described with reference to FIG. The transfer / fixing belt unit 06 includes a transfer / fixing belt 061, a driving roller 062, and a first transfer roller 06.
3, transfer fixing roller 064, tension roller 065,
It comprises a belt cleaner 066, a belt cooling device 068, and the like. As can be seen from the figure, the transfer fixing roller 064 and the driving roller 0
The first transfer position 1000 is located on the side surface of the transfer fixing belt unit 06 on the upstream side in the sheet transport direction, and the second transfer position 20 is located at the lowest position.
00.

As a material of the transfer fixing belt 061, a seamless belt using a thin sheet of a heat-resistant resin such as polyimide, polyetherimide, or polyethersulfone is used. The surface may be coated with fluorine or silicon. The material of the first transfer roller 063 is a material obtained by adding lithium perchlorate to a polyurethane elastomer, a material obtained by adding lithium perchlorate to a polyester elastomer, and a conductive carbon black to urethane rubber around a shaft core such as aluminum. In each case, an elastic layer having a volume resistance of 10 4 to 105 Ω · cm and an Asker C hardness of about 50 to 80 ° is used. The transfer fixing roller 064 uses an aluminum shaft.
The belt cleaner scrapes the toner remaining on the transfer fixing belt 061 with a blade pressed against the belt surface.

The material of the second transfer roller 07 is the same as that of the first transfer roller 07.
As in the case of the transfer roller 063, a polyurethane elastomer with lithium perchlorate added, a polyester elastomer with lithium perchlorate added, and a urethane rubber with conductive carbon black added around the shaft core of aluminum or the like And so on, all have a volume resistance of 10 ⁴ to 1
0 ⁵ Ω · cm, use those provided with the elastic layer about Asker C hardness 50 to 80 °.

The flow of transfer from the image forming means to the transfer / fixing belt and from the transfer / fixing belt to the paper will be described. The toner image formed on the photosensitive drum 051 is transferred to the transfer fixing belt by a voltage having a polarity opposite to that of the toner applied to the first transfer roller 063 and an electric field generated by the photosensitive drum 051 at the first transfer position 1000. 061. At the second transfer position 2000 due to the rotational movement of the toner image on the transfer belt, the toner image is conveyed by the voltage of the opposite polarity to the toner applied to the second transfer roller 07 and the electric field generated by the transfer fixing roller 064. Transferred to paper. The photoconductor drum 051 is in contact with the transfer fixing belt 061,
A moderate nip is formed. Transfer fixing roller 064
Is made of natural rubber, fluoro rubber,
A rubber material such as silicone rubber, a phenol resin, an epoxy resin, a urethane resin, a resin layer of polyester, polyamide, polystyrene, polyacetal, or the like is used. By incorporating the fixing heater 0641, the temperature is controlled to a predetermined temperature required for fixing. The second transfer roller 07 and the transfer fixing roller 064 are pressed against each other by an appropriate pressure.
The unfixed toner is transferred to the nip formed by the two rollers, and the sheet is fixed by being nipped and pressed. The first transfer roller 063 and the second transfer roller 0
As for the voltage applied to 7, an appropriate voltage of about 1 to 6 kV is applied from a high-voltage transformer. Further, the second transfer roller 07 and the transfer fixing roller 064 may be formed of the same material. Further, the fixing heater 0641 incorporated in the transfer / fixing roller 064 may be built in the second transfer roller 07 and may not be incorporated in the transfer / fixing roller. The paper on which the toner image has been fixed is sequentially discharged to the paper discharge tray 10 by the discharge means 09.

The toner remaining on the transfer fixing belt 061 without being completely transferred is scraped off and collected by a belt cleaner 066 having a blade.

A belt cooling device 068 is provided downstream of the belt cleaner 066 in the belt rotation direction. The belt cooling device 068 is configured by a roller that comes into contact with the transfer fixing belt 061, and the roller absorbs heat of the belt. This roller is preferably made of a material having a large heat capacity such as aluminum. The belt cooling device 068 may be configured by a cooling fan instead of a roller. Further, a cooling fan can be used in combination with the belt cooling device 068 of this embodiment. Other transfer fixing belt 0
As long as it can cool 61, they can also be used.

The paper output tray 10 will be described again with reference to FIG. The apparatus is provided with a paper discharge tray lift means 101, and can raise and lower the paper discharge tray 10 as needed. This is because, in the layout of this case, the discharge position is a low position,
When the user takes the printed paper, it is difficult to take it at a lower position, so the final paper of the job is lifted to the position shown by the broken line in the figure after the paper is discharged. Further, even if the next job is entered and printing is started in a state where the printed sheet is not removed, control is performed so as to return to the original discharge position again.

[0046]

According to the first aspect of the present invention, the transfer / fixing belt unit is vertically disposed, and the toner is transferred from the transfer / fixing belt to the paper at the lowermost position of the transfer / fixing belt. In addition, the space for transferring the toner image to the paper is shortened, and the transfer and the fixing are performed at the same time. Therefore, the distance between the registration roller and the discharge unit can be shortened, and the paper conveyance distance is shortened. In addition, by using a single paper cassette that is frequently used, and by making the paper feed position to discharge substantially in a straight line, the paper transport distance is further reduced and the transport path is not bent, so that jams can be reduced.

According to the second aspect of the invention, the space can be further reduced by using the developing device that is vertically arranged.

According to the third aspect of the present invention, since the toner storage container is laid out above the transfer fixing belt and the developing device, the space formed by the toner storage container, the transfer fixing belt and the developing device becomes vertically long, The space for transferring the toner image to the toner becomes shorter. According to the fourth aspect of the present invention, by using the cooling means for cooling the transfer fixing belt, the belt heated during fixing can be cooled.

According to the fifth aspect of the present invention, since a plurality of simplified paper feed trays are used for paper feeding other than the main paper storage unit, it is sufficient to feed rarely used paper from here. In addition, since a plurality of the simplified paper feed trays are prepared, it is possible to set a plurality of types other than the main paper. In the related art, even a sheet of the less frequently used paper occupies one paper storage unit, and therefore, the number of main paper sheets that are frequently used is limited because of the less frequently used paper. Had added. For example, if the usage rate of the main sheet is 95%, 95% of the sheets that can be set in the entire copying machine may be the main sheet. That is, since the usage rate of the papers other than the main paper is less than a few percent of the whole, it is sufficient to feed the other papers from the bypass at any time, which is often more convenient for the user. Further, although the usage rate of the sheets other than the main sheet is low, the types of each sheet are large (small kinds and many kinds). Therefore, a plurality of simplified trays are provided. In conventional bypass paper feeding, only one type of paper was set. In this case, however, it is better to provide a plurality of bypasses which do not require much manufacturing cost, and to provide more types of paper in a smaller space than to provide a plurality of paper storage units. Can be set. Further, since these simplified paper feed trays are located above the main paper storage unit, the paper is conveyed from above to below, so that the slip of the conveyance rollers can be reduced, and the occurrence of jams is reduced.

According to the sixth aspect of the present invention, since the sheet is conveyed in a downward direction from above, the sheet is discharged to a lower position. Therefore, this is compensated for by lifting the discharge tray. This is because, if a paper path is provided and the paper is discharged upward, paper that may be curled after fixing is conveyed from the bottom to the top. The ejected paper does not jam. In addition, when many sheets are accumulated in the sheet discharge tray, the sheet can be lowered.

According to the seventh aspect of the present invention, by using a large-capacity paper cassette in the paper storage unit and being built in the main body of the image forming apparatus, the distance from paper feeding to paper discharging can be further reduced. Can be. Furthermore, by using a drawer that can be pulled out over the entire surface, a space in the left-right direction is not taken up much. This is because the front loading system includes a special cassette, but the size is considerably large. If expensive but extremely stable paper feeding means such as air paper feeding is used for the large-capacity paper feeding cassette having only one, there is no doubt that a jam is further reduced.

As described above, when an image forming apparatus having a new layout as in the present invention is used, jams can be reduced. Further, even when a jam occurs, since the conveyance path is short, the location where the jam occurs can be easily specified, and an image forming apparatus which can easily perform the processing can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an image forming apparatus of the present invention.

FIG. 2 is a schematic diagram of a large capacity paper cassette and air feeding according to the present invention.

FIG. 3 is a schematic diagram of an image forming unit, a transfer and fixing belt unit, and a second transfer roller of the present invention.

FIG. 4 is a schematic diagram of an image forming apparatus according to a related art <conventional example 1>.

FIG. 5 is a schematic diagram of an image forming apparatus according to a related art <conventional example 2>.

FIG. 6 is a schematic view of an image forming apparatus according to a related art <conventional example 2>.

[Explanation of symbols]

 01; large-capacity paper cassette 02; paper supply means 03; registration roller pair 04; transport path 05; image forming means 051; photoconductor drum 052; main charging device 053; exposure means (LPH or LSU) 054; 056; Drum cleaner 057; Toner container 06; Transfer fixing belt (vertical) 061; Belt 062; Drive roller 063; First transfer roller 064; Transfer fixing roller 066; Belt cleaner 068; Belt cooling device 07; Second transfer roller 08; fixing means 09; discharge roller 10; discharge tray 11, general-purpose tray 111; large-size tray 112; medium-size tray 113; small-size tray 1000; first transfer position 12 ; Bypass conveyance path 21; digital optical system 22; automatic document feeder

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Claims (7)

[Claims] A sheet storage unit for storing a plurality of sheets, a sheet feeding unit for feeding sheets stacked in the sheet storage unit to a conveyance path, and a developing roller for forming a toner image on a photosensitive drum. An electrophotographic image forming means having a developing device provided thereon, and a toner image formed by the image forming means is transferred at a primary transfer position, and the toner image is transferred to a paper at a secondary transfer position. In an image forming apparatus having a transfer-fixing belt that is nipped and heated by an opposing pressure roller at a secondary transfer position and fixed by heating, and a discharge unit that discharges a sheet, the transfer-fixing belt is directed substantially upward. Vertically arranged, secondary transfer is performed at the lowermost position of the transfer fixing belt,
The image forming apparatus according to claim 1, wherein a position of the sheet feeding unit, a position of transfer to the sheet, and a position of the discharging unit are substantially straight. 2. The image forming device according to claim 1, wherein a developing roller faces a substantially upper direction of the photosensitive drum and a vertical developing device in which a stirring device is arranged in a substantially vertical direction. 2. The image forming apparatus according to 1. 3. The image forming apparatus according to claim 1, wherein a toner container is laid out above the developing device and the transfer fixing belt. 4. The image forming apparatus according to claim 1, further comprising a transfer / fixing belt cooling unit for cooling the transfer / fixing belt. 5. An upper portion of the paper storage section has a plurality of simplified paper feed trays and a common single bypass conveyance path, and paper can be selectively fed from the plurality of simplified paper feed trays. 2. The apparatus according to claim 1, wherein the bypass conveying path smoothly merges in a conveying direction from an obliquely upward direction downstream of the paper feeding unit of the paper storage unit and upstream of the resist.
5. The image forming apparatus according to any one of claims 1 to 4. 6. A discharge tray lifting means for lifting a discharge tray to a first discharge position for discharging the discharge tray and a second discharge position at which a user can easily discharge the discharged paper. The image forming apparatus according to claim 1, further comprising: 7. The image forming apparatus according to claim 1, wherein said sheet storage section can load a large amount of sheets of paper, is built in the image forming apparatus main body, and can be pulled out to the front. .